Process of producing esters



Patented May 7, 1946 UNITED STATES PROCESS OF PRODUCINGESTERS NathanielBeverley Tucker, Louisville, Ky., assignor to The Procter & GambleCompany, Cinclnnatl, Ohio, a corporation of Ohio No Drawing. ApplicationJuly 2, 1942,

Serial No. 449,497

18 Claims.

This invention relates broadly to the production of carboxylic acidesters.

It is an object of this invention to provide an improved process for theproduction of carboxylic acid esters.

In my copending applications, Ser. No. 387,985, filed April 10, 1941,now Patent 2,289,391, and Ser. No. 422,684, filed December 12, 1941, nowPatent 2,342,562, I have shown that salts of fatty acids and halogensubstituted alkyl metal sulfonates react at a higher rate and to agreater degree of completion when the condensation is conducted in thepresence of certain amides or substituted amides derived frommonocarboxylic acids. I have now found that with reactions which do notinvolve sulfonate at all, the use 01' amides of a certain class asreaction media have useful application whenever it is desired to producean ester of a carboxylic acid by reaction of a carboxylate salt and ahalogen acid ester of an aliphatic alcoholic hydroxy compound free ofsuli'onate groups, such as for example in cases 1) where the aliphatichalide is more generally available than the corresponding alcohol, as inthe case of chlorinated lower molecular weight I olefins, chlorinatedparaffins and chlorinated kerosene fractions, and (2) where it isdesired to form an ester of a hydroxy carboxylic acid, in whichreaction, self esteriflcation and resulting polymerization is likely tooccur when the hydroxy carboxylic acid is subjected to esterificationconditions with an alcohol for example.

Ordinarily reactions involving the condensation of metal carboxylatesand halide esters herein referred to progress relatively slowly, in someinstances even at temperatures in the neighborhood of 200 C., andconsequently products of condensations conducted in accordance with thepractice heretofore known in the art either have contained unreactedingredients because of too short a time of reaction or too low areaction temperature, or have contained undesirable by-productsincluding decomposition products because oi. too long a reaction time Ortoo high a reaction temperature. Consequently preparations oi the priorart practices have usually resulted in low yield of ester and haverequired extensive puriflcation to recover same from the reaction mix.

These disadvantages of prior art methods are in large measure overcomeby my invention in accordance with which the ester is formed by thecondensation of the carboxylate salt and the aliphatic halide in thepresence of a substantial amount of an inert reaction medium consistingessentially of an amide compound in which both reactants are at leastpartially soluble and which has the general formula-R-CO-NRR"wherein R.is alkyl, aryl, or hydroxy alkyl, and R and R" are radicalsselected fromthe group consisting ot'hydrogen, alkyl, aryl, hydroxy alkyl, andalkylene, R and R" each being alkylene only when the other is alkyleneand being joined together through an oxygen atom (-R-O-R").

The highly advantageous action of the reaction medium in thecondensation reaction above identified is not due solely to the solventaction which the amide or substituted amide has for the reactants,because I have found that ethylene glycol and other materials which areexcellent solvents for both reactants do not function in the same manneras the amides and substituted amides herein covered, but in contrastthereto result in lower yields of -esteriiication products which arecontaminated so highly with unreacted salt and other detrimentalimpurities that purification by crystallization from a solvent is 215essential if substantially pure products are desired. Apparently theamide or substituted amide which I use in accordance with my inventionpossesses a characteristic or combination of characteristics such ascatalytic effect in combination to with solvent eflect, making this typeof com und especially suitable for the purpose at hand because, as faras I am aware, there are no other compounds which function in the samemanner as the amides and substituted amides covered 85 herein to givethe highly advantageous result of the present invention.

In the preferred practice of my invention the carboxylate salt is heatedwith the aliphatic halide in the presence 01' a suflicient amount of 40amide or substituted amide a the reaction methe reaction medium mayberemoved by distillation from the mixture at atmospheric orsubatmospheric pressure, but at a temperature below that at which thereactants or products decompose. If the amide employed cannot be readilyremoved from the reaction product by distillation, then purification bycrystallization from a solvent or by extraction with a selective solventmay be eilected if desired.

My invention and the manner in which it may be practiced will be clearfrom the following 'examples in which specific conditions of operationare set forth. However it is to be understood that these examples aremerely exemplary and that the invention is not limited to the conditionsor the reactants described, but rather to the scope of the appendedclaims.

Example 1.-22 parts sodium coconut oil soap, 18 parts decyl chloride,and 40 parts butyramide were agitated at 140 C. for about 16 hours. Thereaction product was mixed with aqueous alcohol and extracted withpetroleum ether. Evaporation of the petroleum ether extract yielded aproduct which, without further purification, had an acid value of 0.6and a saponiflcation value of 138.2.

Example 2.-13 parts benzyl chloride, 23 parts sodium coconut oil soap,and 50 parts acetamide were heated at 140 C. to 150 C. for 5 hours, atwhich time the reaction was complete as indicated by titration for ionicchlorine. The reaction mix was introduced into water and extracted withether, the etherextract being subsequently water washed. On evaporationof the ether a product having an acid value 01' 9.0 and a saponiflcationvalue of 203.7 was obtained.

Example 3.-70 parts oi. dried and ground dry sodium coconut oil soap and150 'parts acetamide were mixed and heated to 140 C. and agitated untiluniform, after which 15 parts of 1,2;3-trichiorpropane were introducedinto the reaction mix rapidly. After 1% hours at 140 C. equilibrium wasreached as indicated by tritrations for ionic chlorine. The reactionproduct was mixed with water and extracted four times with ether. Theether extract was subsequently washed with water, filtered andevaporated. The product without further purification contained 6.2%chlorine by analysis.

Example 4.--23 parts of oven dried sodium coconut oil soap, 12 parts ofn-amyl chloride, and 50 parts of acetamide were mixed and agitated at170 to 180 C. for 8 hours, after which the reaction product was added towater and extracted with ether. The ether extract was water washed andevaporated to yield a product having an acid value of 12.7 and asaponification value of 203.4.

Example 5.-22 parts of sodium coconut oil soap, 20 parts of an alkylchloride resulting from the chlorination of a, kerosene fraction havingan average of 12 carbon atoms per molecule, and 40 parts of theethanolamide derived from the fatty acids obtained from coconut oil wereheated at 180 C. for 7 hours, at the end of which time titration of thereaction mix for ionic chlorine indicated 95% completion of thereaction.

Example 62-40 parts of the alkyl chloride used in Example 5, 44 parts ofdied coconut oil soap, and 40 parts of capramide were heated at 180 C.for 24 hours. After the reaction had reached 92% completion asdetermined by titration for ionic chlorine, the bulk of the amide wasremoved by distillation at one millimeter pressure and the residue wasintroduced into water and extracted with petroleum ether. Uponevaporation of the petroleum ether solvent a brown oil having an acidvalue of 7.7 and a saponiiication value of 170.5 was obtained.

Example 7.92 parts of dry sodium coconut oil soap, 50 parts ofmonochlorhydrin, and 200 parts of acetamide were heated and stirredtogether at C. for 90 minutes. The reagents went into solution promptlybut the mix soon clouded due to the precipitation of sodium chloride.The ac'etamide was distilled 011 in vacuum at a temperature of C., thefat taken up in ether, filtered, washed with water and dried. Thepurified product had an acid value of 14.2, a saponification value of217.9, and a hydroxyl value or 317. A sample of the product yieldedabout 29% glycerin on hydrolysis. These analyses show that the productof reaction consisted almost wholly of coconut oil monoglyceride.

The above examples are sufllcient to illustrate the manner in which theinvention may be practiced and it will not be necessary to show by wayof specific examples the various modifications and combinations that canbe made.

My process is especially useful for making the esters of higher fattyacids having eight to twenty-two carbons per molecule such as lauric,palmitic, oleic and those mixed acids obtainable from the naturallyoccurring vegetable and animal fats and oils, and of polyhydric alcoholsor other alcohols having limited miscibility with the fatty acids.However, I may employ in my process halides corresponding to otheralcohols and salts of other carboxylic acids. For instance, my processis particularly applicable to the preparation of esters of hydroxyacids, such as hydroxy acetic acid, which on direct esterification withan added alcohol undergo esterification at the hydroxyl group of theacid in addition to esterification between the acid and the addedalcohol. This complication may be avoided when an ester of such an acidis made by my process.

Also, -it should be noted that in addition to alkali metal carboxylatesalts, alkaline earth metal salts such as calcium and magnesium salts,or even some heavy metal salts, may be used provided the metal is suchthat it readily combines with the halogen of the halogen acid' ester toproduce a neutral salt.

In the examples I have shown throughout the reaction of chlorides withthe carboxylate salts merely because these derivatives are readilyavailable or easily prepared. However, other aliphatic halides such asbromides and iodides may be employed with equal ease without departingfrom the spirit of the invention.

Furthermore, the term "aliphatic halide as used in the specification andclaims, unless otherwise designated, is intended to include halidederivatives of alkyl compounds generally such as lauryl iodide,methallyl bromide, etc., of aryl-substituted alkyl halides such asbenzyl chloride, and of other aliphatic compounds free of sulfonategroups both saturated and unsaturated. In this connection I desire topoint out that there are unsaturated compounds coming within the broadterminology above defined, such as vinyl halides (C:CX) which are veryinactive and do not react efliciently with carboxylate salts. Even inthese cases the presence of the amide is of some benefit, but theimportant applications of the process or my invention reside in thecondensation of the more active halides with the carboxylate salts.

It has been stated above that the amides or substituted amides which.may be employed in my invention are those which do not take part in thereaction herein involved but which at least partially dissolve thereacting compounds. Speciilc examples of amides and substituted amideswhich may be employed in accordance with the invention are as follows:

Benzamide Acotaniiide CH -C- t CH -NHs Propionamide O C slit-1 1 NButyramido 0 CHrCH--NH:

Isobutyramide o 0.1;. C Hs-( J-N CQHI Diethylacetamide 0 H CH1- ("3 -N 01H: 0 H Ethanolacetamide- 03m Aoety] morpholine C :H t C nHaC O -N OCaHe N-Lauroyl morpholine Amide of capric acid C H- C 0 NH,

Amide oi lauric acid CIIHI'I'Cb NH'CHQOH Monoethanoiamide oi myristicacid CeHn-CO-NH-CHrCHOH-CHaOII A Monoglycerylamide ol capric acid CHH -CO-NH-CH:

I Methyl lam-amide CnHa-CO-NH-CsHn Ethyl lauramide CeHu-C 0 -NH-CaH1Monopropyl amide oi capric acid ClH rCO-NH-C4H| Monobutyl amide oicapric acid nHnC (CHs):

Dimethyl amide of myristic acid CuHfl- C O-N- (Chm) Diethyl amide oilauric acid C Ha-C O -N Methyl ethyl amide oi lauric acid CoHu- C O -NCsH'l Methyl propyl amide of capric acid In general, amides which atleast partially dissolve both reactants will efiect some improvement inthe reaction but all amides are not equally eilicient in all reactions.For example, I have found that in the reaction between coconut oil soapand the kerosene chloride of Example 5 a higher molecular weight amidecompound, such as the amide of the mixture of coconut oil fatty acidsconsisting predominantly of fatty acids having ten to fourteen carbonatoms, dissolves the reactants to a greater degree than .the amidecompounds of lower molecular weight and thus are better suited to thatparticular condensation. Thus there may be a preference for one amidecompound over another in some instances.

In the practice of my invention I prefer to employ the lowest possibletemperature at which the reaction will proceed readily and at which noserious decomposition of reactants or products takes place. In someinstances the reaction may be conducted at temperatures as low as C.: inother instances higher temperatures are required, such as C., and in thecase of the reactions involving the use of higher molecular weightchlorides temperatures in the neighborhood of C. may be necessary. Inall cases the presence of the amide efiects an improvement in thereaction rate and an improved yield of desired product.

- The amount of amide or substituted amide which should be employed isnot critical. I have found that in some instances an amount less thanhalf the weight of the mixture of carboxylate salt and halogensubstituted compound will be sumcient; in other cases, especially thosewhere the solubility of the reactants in the amide is low, I have foundthat the use of a larger amount of reaction medium, such as an amountequal to the combined weights of the reactants or an amount which ismuch larger, even four to six times the combined weight, may benecessary. An excess of amide is not harmful.

Having thus described my invention, what I claim and desire to secure byLetters Patent is:

1. The process claimed in claim 15, in which the amide is one in which Rand R" are both hydrogen.

2. The process claimed in the amide is acetamide.

3. The process claimed in claim 15, in which the metal salt is a soap ofa saponiflable natural fat and the halogen acid ester is the hydrogenchloride ester of a saturated aliphatic alcoholic hydroxy substance.

4. The process claimed in claim 15, in which the metal salt is sodiumcoconut oil soap, the halide ester is monochlorhydrin, and the amide isclaim 15, in which acetamide.

5. The process claimed in claim 15, in which the amide is aN-di-substituted amide.

6. The process claimed in claim 15, in which the amide is aN-di-substituted amide. derived from a mixture of fatty acids containedin coconut oil and consisting predominantly of fatty acids having ten tofourteen carbon atoms per molecule.

7. The process claimed in claim 15, in which the amide is derived frommorpholine and a mixture of fatty acids contained in coconut oil andhaving ten to fourteen carbon atoms per molecule.

8. The process claimed in claim 15, in which the amide comprisesessentially the amide of morpholine and lauric acid.

9. The process claimed in claim 15 in which the metal salt is sodiumcoconut oil soap and the halide ester is a chloride derived from akerosene fraction.

10. The process claimed in claim 15, in which the metal salt is sodiumcoconut oil soap, the halide ester is the chloride derived from akerosene fraction consisting predominantly of hydrocarbons having twelvecarbon atoms per molecule, and the amide comprises essentially the amideof morpholine and lauric acid.

11. The process claimed in claim 15, in which the amide is the amide ofa mixture of fatty acids of coconut oil consisting predominantly offatty acids having ten to fourteen carbon atoms.

12. The process claimed in claim 15, in which the amide comprisesessentially lauramide.

13. The process claimed in claim 15, in which the metal salt is sodiumcoconut soap and the' halide ester is n-amyl chloride.

14. The process claimed in claim 15, in which the metal salt is sodiumcoconut soap, the halide ester is n-amyl chloride, and the amidecomprises essentially lauramide.

15. In the process of condensing a metal salt of a fatty acid having 8to 22 carbon atoms and an aliphatic halide free of sulfonate groupswherein an ester and a neutral salt are formed, the improvement whichcomprises conducting the condensation in the presence of an amide whichdoes not enter into the reaction but which ,at least partially dissolvesthe reactants and which has the formula R-CO-NR'R" wherein R is aradical of the group consisting of alkyl, aryl, and hydroxy alkyl, and Rand R" are selected from the group consisting of hydrogen, alkyl, aryl,hydroxy alkyl, and alkylene, R and R" each being alkylene only when theother is alkylene and then being Joined together through an oxygen atom.

16. In the process of condensing a metal salt of a fatty acid having 8to 22 carbon atoms and an aliphatic halide free of sulfonate groups andselected from the group consisting of aliphatic chlorides. bromides, andiodides, in which condensation an ester and a neutral salt are formed,the improvement which comprises conducting the condensation in thepresence of an amide which does not enter into the reaction but which atleast partially dissolves the reactants and which has the formulaR-CO-NR'R" wherein R is a radical of the group consisting of alkyl,aryl, and hydroxy alkyl, and R and R" are selected from the groupconsisting of hydrogen, alkyl, aryl, hydroxy alkyl, and alkylene, R andR" each being alkylene only when the other is alkylene and then beingjoined together through an oxygen atom, and thereafter separating theester from the condensation mix.

17. In the process of condensing a metal salt of a fatty acid having 8to 22 carbon atoms and an aliphatic halide free of sulfonate groups andselected from the group consisting of aliphatic chlorides, bromides, andiodides, in which con,- densation an ester and a neutral salt areformed, the improvement which comprises conducting the condensation inthe presence of an amide which does not enter into the reaction butwhich at least partially dissolves the reactants and which has theformula RCO-NR'R" wherein R is a radical of thegroup consisting ofalkyl, aryl, and hydroxy alkyl, and R and R" are selected from the groupconsisting of hydrogen, alkyl, aryl, hydroxy alkyl, and alkylene, R andR" each being alkylene only when the other is alkylene and then beingjoined together through an oxygen atom, and thereafter distilling offthe amide under conditions of temperature and pressure which will notresult in substantial decomposition of the said condensation product.

18. In the process of condensing a metal salt of a fatty acid having 8to 22 carbon atoms and an aliphatic halide free of sulfonate groups andselected from the group consisting of aliphatic chlorides, bromides, andiodides, in which condensation an ester and a neutral salt are formed,the improvement which. comprises conducting the condensation in thepresence 01' an amide which does not enter into the reaction but whichat least partially dissolves the reactants and which has the formulaR-CO-NRR" wherein R is a radical of the group consisting of alkyl, aryl,and hydroxy alkyl, and R and R" are selected from the group consistingof hydrogen, alkyl, aryl, hydroxy alkyl, and alkylene, R and R" eachbeing alkylene only when the other is alkylene and then being joinedtogether through an oxygen atom, and thereafter separating the amidefrom the condensation product with the aid of a solvent.

NATHANIEL BEVERLEY TUCKER.

